<?php
interface MyExceptionInterface
{
	public function doit();
}

class MyException extends Exception
{
	public function __construct(MyExceptionInterface $objExcepion = NULL)
	{
		echo 'runrun--';
		if ( $objExcepion != NULL) {
			$objExcepion->doit();
		} else {
			echo 'hoge';
		}
	}
}